Use ArcFileSystemInstance to access files on ARC.

components/arc/test/fake_file_system_instance.h

Index: components/arc/test/fake_file_system_instance.h
diff --git a/components/arc/test/fake_file_system_instance.h b/components/arc/test/fake_file_system_instance.h
new file mode 100644
index 0000000000000000000000000000000000000000..9137faff17eeb93f95d9d9e838118c9a4268059e
--- /dev/null
+++ b/components/arc/test/fake_file_system_instance.h
@@ -0,0 +1,37 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_ARC_TEST_FAKE_FILE_SYSTEM_INSTANCE_H_
+#define COMPONENTS_ARC_TEST_FAKE_FILE_SYSTEM_INSTANCE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+#include "components/arc/common/file_system.mojom.h"
+
+namespace arc {
+
+class FakeFileSystemInstance : public mojom::FileSystemInstance {
+ public:
+  FakeFileSystemInstance();
+
+  // mojom::FileSystemInstance:
+  ~FakeFileSystemInstance() override;
+
+  void GetFileSize(const std::string& url,
+                   const GetFileSizeCallback& callback) override;
+
+  void OpenFileToRead(const std::string& url,
+                      const OpenFileToReadCallback& callback) override;
+
+  void RequestMediaScan(const std::vector<std::string>& paths) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FakeFileSystemInstance);
+};
+
+}  // namespace arc
+
+#endif  // COMPONENTS_ARC_TEST_FAKE_FILE_SYSTEM_INSTANCE_H_